Table of Contents

Abstract: n/a

Abstract: The tetramethyldibenzocyclam derivative, was synthesized and characterized and was used for fabrication of potentiometric sensor for Ni²⁺ metal ion. 5,7,8,14-tetramethyldibenzo[b,i]-1,4,8,11-tetrazacyclotetradecanenickel(II)chloride, ([Ni(Me₄Bzo₂[14]ane N₄)]Cl₂) (II) was obtained in good yield as orange red salt by Fe/HCl reduction of the corresponding tetraazaannulene complex [Ni(Me4Bzo₂taa)], (I). Membrane having [Ni(Me₄Bzo₂[14]aneN₄)]Cl₂ (II) as electroactive material, sodium tetraphenylborate (NaTPB) as an anion discriminator, dibutyl butylphosphonate (DBBP) as plasticizer in PVC matrix in the percentage ratio 5.0:2.5:200:200 (II:NaTPB:DBBP:PVC)(w/w) exhibits a linear response to Ni²⁺ in the concentration range 7.0×10^-6- 1.0×10^-1M with a slope of 29.8±0.2 mV/decade of activity and a fast response time of 12s. The sensor works well in the pH range 2.0-7.6 and can be satisfactorily used in presence of 40% (v/v) methanol, ethanol or acetone. The sensor is highly selective for Ni²⁺ over a large number of mono-, biand trivalent cations. The sensor has been successfully used as indicator electrode in the potentiometric titration of Ni²⁺ against EDTA. These electrodes can be used to determine the concentration of Ni²⁺ in real samples.

Abstract: This review discusses molecular design principles of calixarene-type macrocycles for ion recognition and gives examples on the relationship between structure and selectivity, however without attempting to cover all the different approaches.

Abstract: The preparation of polymer membrane selective to silver ion and its application to ion-selective electrode is reported here. PVC membrane contain silver-selective calix[4]arene derivative as ionophore. The membrane electrode is highly selective to silver ion and exhibit good linear response over a wide concentration range of 1.0×10^-1 to 1.0×10^-5M AgNO₃ with Nernstian slope of 58.9 mV per decade. The detection limit of electrode is 6.31×10^-6 M .The calix[4]arene based membrane electrode exhibit enhanced selectivities for silver ion over other cations; log K^Pot_Ag,Na = -2.35, log K^Pot_Ag,K= -2.65, log K^Pot_Ag,Mg = -4.57, log K^Pot_Ag,Ba = -4.10, log K^Pot_Ag,Cd = -3.42, log K^Pot_Ag,Pb = -3.45.Even the strongest interferent Hg²⁺ do not interfere to great extent, log K^Pot_Ag,Hg = -2.0.The electrode response is stable over wide pH range of 1.0-6.0. The response time of the sensor is 30 seconds and the membrane can be used for more than 6 months without observing any divergence. The sensor can also be applied as an indicator electrode for potentiometric titration of Ag⁺ ions with Cl^-. It is possible to determine Ag(I) in the natural water spiked with silver with this electrode assembly.

Abstract: A plastic membrane electrode for the determination of methacycline hydrochloride was fabricated based on the use of methacycline-tetraphenylborate as the electroactive substance, and dioctylphtalate as the plasticizing agent. It was found that the potential responses of the electrode were influenced by pH of the tested solution when pH>3. Under the condition of pH 2.6, the linear response range, slope (25ºC) and detection limit obtained were 3.0×10^-2~6.0×10^-6M, 52.9mv per decade and 3.4×10^-6M ,respectively. The response time of the electrodes was <15 seconds. The values of recovery obtained were 99.2~101.2%. The electrode was successfully applied to determination of methacycline hydrochloride in tablet by direct potentiometric method. The result obtained with the electrode was in good agreement with the value obtained by using the official method (highperformance liquid chromatography).

Abstract: The measurement of lithium in blood serum requires high selectivity since the blood contains about 140 mM sodium compared to the 0.5-1.5 mM lithium level in manic depressive patients under treatment with lithium salts. This review traces the development of optical and potentiometric methods for the selective measurement of lithium in the presence of sodium. Selectivities of over 1,000:1 are achievable with properly designed ionophores.